Ultrasound

Echographic Evaluation of Splenic Injury after Blunt Trauma" w. Michael Asher, M.D., Steve Parvin, M.D., Richard W. Virgilio, M.D., and Kai Haber, M.D. In a significant number of patients with blunt abdominal trauma, the diagnosis of ruptured spleen is not readily apparent. It is in these cases that echographic evaluation appears to aid significantly in diagnosis. Seventy patients with blunt abdominal trauma were studied by echography. Results indicated 61 true negative cases, 1 false negative, 4 true positives, and 4 false positives. Criteria for splenic ruptures are set forth. Ultrasound is considered to be an excellent screening procedure for suspected splenic rupture. INDEX TERMS:

Spleen, angiography. Spleen, ultrasound. Spleen, wounds and injuries

Radiology 118:411-415, February 1976

• of the signs of blunt abdominal trauma and the difficulty in its accurate clinical assessment logically make it an appropriate target for echographic study. The usual pathological process involves rupture of a viscus, which results in a change in the normal morphology of the organ. Changes in the expected anatomical configuration of an organ and identification of the surrounding fluid or other soft tissues may be encountered in images of ruptured viscera. Because of the relatively high frequency of splenic injury in blunt thoraco-abdominal trauma (1, 5), evaluation of the spleen seemed to be in order.

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HE OFTEN SUBTLE NATURE

examinations were carried out with conventional leading-edge or gray-scale equipment with a 2.25-MHz transducer. Each patient was scanned in the supine position. Whenever the patient's clinical condition permitted, scans were carried out in the prone and right lateral decubitus positions. Scanning was performed in the transverse direction. No significant difference was observed between the results of gray scale and conventional echograms, and we feel that hematomas can be detected by either instrument.

RESULTS

MATERIALS AND METHODS

Five hundred consecutive patients with blunt abdominal trauma severe enough for hospitalization were evaluated by a special trauma unit in the emergency room at San Diego Naval Regional Medical Center. Each patient underwent diagnostic peritoneal lavage for hemorrhage; the technique and results are described elsewhere (8, 10). Of these 500 peritoneal lavages, 68 were strongly positive, 99 were weakly positive, and 333 were negative. Patients with negative peritoneal lavages underwent no further diagnostic studies. A total of 70 patients were studied by echography. Seven of them were from the group which had strongly positive peritoneal lavage, 63 from the weakly positive group. All weakly positive or trace positive patients were examined. The remaining patients with strongly positive lavage findings were those with obvious acute abdomenal injury requiring emergency surgical intervention. Celiac or splenic angiography was carried out in all patients with positive sonograms and in 30 patients with negative sonograms. Ten patients had angiography but no echography. Compound contact B-scan ultrasound

Each ultrasound examination was interpreted by two of the authors (W. M. A. and K. H.) independently. There was agreement initially in 60 of the 70 echograms. In the remaining 10 the two observors had only minor differences of opinion which were readily resolved and resulted in a consensus. Eight echograms were interpreted as being positive for splenic rupture. Four of these patients did indeed have ruptured spleens and positive angiograms. The remaining four all had negative angiograms and a subsequent benign clinical course, with a minimal follow-up of three weeks. This indicates that there were four false positive examinations in this study. Sixty-two echograms were interpreted as normal with no evidence of significant injury to the spleen. Of these, 61 subsequently were shown to be normal either at surgery or as a result of a benign clinical course; 29 also had negative angiograms. One patient had a negative sonogram and a negative angiogram and deteriorated clinically several hours after the diagnostic studies. At laparotomy a ruptured spleen was found. Thus we encountered only one false negative sonogram.

1 From the Departments of Radiology, Naval Regional Medical Center (W. M. A.), San Diego, Calif., University of Arizona Medical Center (K. H., James Picker Foundation Scholar), Tucson, Ariz., and Surgery, Naval Regional Medical Center (S. P., R. W. V.), San Diego, Calif. Presented at the Sixtieth Scientific Assembly and Annual Meeting of the Radiological Society of North America, Chicago, 111., Dec. 1-6, 1974.

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Fig. 2. Transverse scan in the prone position shows marked splenic enlargement in this patient with mononucleosis. Fig. 3. Lymphosarcoma. Transverse scan in the supine position reveals splenomegaly and lymphadenopathy. Note the anterior extension of the spleen.

Fig. 4. Supine transverse sonogram of a patient with splenomegaly and large intrasplenic cyst. A. Note the strong echoes from peripheral calcification. There's no increased transmission due to calcification. S. Abdominal radiograph of same patient demonstrates the peripheral calcification. Fig. 1. The serial transverse scans of the normal spleen (5) in the prone position. Note the cyst (c) in the upper pole of the left kidney.

DISCUSSION

Evaluation of the patient with blunt abdominal trauma may be difficult. In most cases of ruptured spleen, the diagnosis is readily apparent clinically. In approximately 10-20 % of cases, the diagnosis is not so apparent (12). In this group of patients, physical examination, laboratory studies, and routine radiography all have significant shortcomings (3). Peritoneal lavage (10) and angiography (3) may be more accurate in the evaluation of splenic rupture; however, they are invasive studies and

occasionally have serious complications. Furthermore, they too may give erroneous diagnostic information. Radionuclide imaging of the spleen may also be of considerable diagnostic value (7, 9). Scanning in either the prone or supine position is best carried out in the transverse direction. This usually gives satisfactory scans and allows visualization of the entire spleen (Fig. 1). Longitudinal scanning often gives inferior images due to rib artifacts in the prone position. For transverse scans, one can angle the transducer in the intercostal spaces. Occasionally one can image the spleen best in the decubitus position. A review of the literature reveals few descriptions of abnormal sonographic splenic imaging (4, 6). No images of splenic rupture from trauma were found. Because of the investigative nature of the study, with no precedent either in our experience or in the literature, echographic

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criteria of splenic injury were worked out empirically. The following parameters were selected: (a) Enlarged Spleen: Enlargement of the splenic echo contour was present in the majority of patients subsequently shown to have splenic rupture. However, one must exercise caution in diagnosing significant splenic trauma on this criterion alone. We found six cases of unrelated splenomegaly in patients without significant intra-abdominal injury. Four of the six had mononucleosis (Fig. 2). One was a known lymphoma patient (Fig. 3) and one had a benign calcified splenic cyst (Fig. 4). Interestingly, despite the reported increased incidence of splenic trauma in patients with prior splenomegaly, none of the patients with splenic rupture in this study had pathological evidence of pre-existing splenic disease. Some difficulty in diagnosing splenomegaly by echography may be encountered. Although volume measurements of the spleen can be obtained, the method is somewhat laborious and not without error (11). One criterion for enlargement was the demonstration that the contour does not extend more than 2 cm anterior to the aorta in the supine position (Fig. 5). This guideline cannot be used in evaluating prone scans, due to the variable mobility of the spleen (Fig. 6). (b) Irregular Border of the Spleen: Irregularity or interruption of the border of the spleen may indicate splenic rupture at that point (Fig. 7). If a portion of the border is absent, one must exclude artifacts such as ribs or interposed gas and be cautious in the evaluation of an irregular medial border, because normally there is a slight amount of irregularity at the hilus (Fig. 8). Furthermore, scanning from the supine position often does not allow the transducer to be positioned so that the ultrasound beam is perpendicular to the often markedly curved surface at each point. Indeed, spurious echoes may be observed and erroneously interpreted as an irregular border sign. Scanning in the prone position allows placement of the transducer over the back. Moving the transducer back and forth in a rocking fashion over the flank and back usually allows visulization of the entire medial surface. Scanning in the prone position also reduces the respiratory excursion of the diaphragm, resulting in fewer motion artifacts in patients not fully able to cooperate. (c) Positional Change in Splenic Contour: When shifted by 90 or 180 0 , a normal spleen shows some change in position in the left upper quadrant; however, the splenic contour does not change significantly. An overtly ruptured spleen or one with adjacent or contiguous (subcapsular) hematoma will occasionally show a marked change in contour with shifting positions. (d) Progressive Enlargement of the Spleen During Sequential Examination: This sign is, of course, not applicable to the initial examination. The diagnosis of splenic rupture can be assured when sequential examinations clearly demonstrate progressive enlargement. (e) Double Contour of the Spleen: The double-contour sign (2) indicates a collection of fluid in a confined

Ultrasound

Fig. 5. Photograph of a thin transverse section through the upper abdomen of a cadaver. Note the posterior location of the spleen. (Courtesy AFIP).

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Fig. 6. Supine and prone scans obtained at same level. Longitudinal scan in the prone position represents a left para sagittal section. Note the mobility of the spleen with shifting positions. S = Spleen; L = liver; V = vertebra.

space. In the case of splenic rupture, the fluid is blood and the confined space is the space between the splenic parenchyma and the intact splenic capsule. If this sign is unequivocally present, the diagnosis of splenic rupture is usually certain (Fig. 9). (f) Free Intraperitoneal Fluid: This sign is nonspecific and may be associated with any cause of fluid within the abdomen; hence it should be correlated with other echographic or clinical signs of splenic rupture. In our

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Fig. 7. Irregular border sign. A transverse supine scan demonstrating marked irregularity of the medial border in a patient with splenic rupture. Fig. 10. Normal transverse scan in prone position. Note the good through transmission of the sonic beam and the lack of internal echoes.

Fig. 8. Prone transverse scan demonstrating an enlarged spleen in a patient with mononucleosis. Note the prominent echoes from the splenic hilus (arrows), which may be difficult to differentiate from an irregular border sign.

Fig. 9. Detailed view of the anterior portion of a transverse supine scan of the upper abdomen. Plain arrows indicate the medial border of the spleen; arrows with dots delineate the splenic capsule. At surgery a ruptured spleen with subcapsular hematoma was found.

study the sign was not helpful due to variable amounts of retained saline following peritoneal lavage. Due to the echo-free nature of the normal spleen (Fig. 10), even a large internal splenic hematoma may be missed. Thus this is not considered a primary criterion. It rapidly became apparent that all of the proposed criteria for ruptured spleen did not carry equal emphasis. Double contour, progressive enlargement, and sple-

nomegaly were the most prominent features. Utilizing the information in this study and experience with three additional cases of splenic rupture noted before or subsequent to this study, we discovered that at least two of the criteria must be met to have reasonable assurance of a ruptured spleen; the presence of more than two criteria, of course, added significantly to diagnostic confidence. Since these criteria are based on morphological abnormalities, simultaneous exclusion of those processes causing splenomegaly (infiltrating diseases) will increase accuracy. Although enlargement by itself is the most sensitive criterion (present in 6 of 7 cases), it is also the most nonspecific for splenic rupture. Eight echograms were interpreted as positive for splenic rupture. Of these, half had no significant splenic injury. The four that proved to have ruptured spleens each had positive arteriograms. The four negative patients all had negative arteriograms. However, angiography showed both false positive and false negative cases in different cases than those demonstrated by echography. Although only four true positive cases were discovered, these were in a preselected group which did not include the obvious surgical candidates and the more severely injured patients. Since there was only one false negative case and 61 true negative cases, sonography is an excellent screening procedure for patients with blunt abdominal trauma in whom rupture of the spleen is suspected. Thus a major value of echography is in selecting those patients who do not need further diagnostic studies. On the other hand, if the sonogram is interpreted as abnormal, further workup is indicated. The current study did not include radionuclide evaluation. However, the literature (7, 9) indicates that it would be a complementary, noninvasive technique for evaluation of patients with positive sonograms. Our previous experience and the experience in this study indicate that the application of the technique on nonselected patients would be a valuable aid in the triage of patients with abdominal injury.

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REFERENCES 1. Fitzgerald JB, Crawford ES, De Bakey ME: Surgical considerations of non penetrating abdominal injuries: an analysis of 200 cases. Am J Surg 100:22-29, Jul 1960 2. Freimanis AK, Asher WM: Development of diagnostic criteria in echographic study of abdominal lesions. Am J Roentgenol 108:747-755, Apr 1970 3. Gold RE, Hoskins PA: Radiologic evaluation of splenic trauma. CRC Crit Rev Radiol Sci 3:453-487, Dec 1972 4. Holm HH: Ultrasonic scanning in the diagnosis of spaceoccupying lesions of the upper abdomen. Br J Radiol 44:24-36, Jan 1971 5. Jordan GL Jr, Beall AC Jr: Diagnosis and management of abdominal trauma. Curr Probl Surg 3-62, Nov 1971 6. Kristensen JK, Buemann B, Kuhl E: Ultrasonic scanning in the diagnosis of splenic haematomas. Acta Chir Scand 137:653657, 1971 7. Nebesar RA, Rabinov KR, Potsaid MS: Radionuclide imaging of the spleen in suspected splenic injury. Radiology 110:609614, Mar 1974

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8. Olsen WR, Redman HC, Hildreth DH: Quantitative peritoneal lavage in blunt abdominal trauma. Arch Surg 104:536-543, Apr 1972 9. O'Mara RE, Hall RC, Dombroski DL: Scintiscanning in the diagnosis of rupture of the spleen. Surg Gynec Obstet 131: 10771084, Dec 1970 10. Parvin S, Smith DE, Asher WM, et al: The effectiveness of peritoneal lavage in blunt abdominal trauma (to be published) 11. Rassmussen SN, Christensen BE, Holm HH, et al: Spleen volume determination by ultrasonic scanning. Scand J Haemat 10: 298-304, 1973 12. Villarreal-Rios A, Mays ET: Efficacy of clinical evaluation and selective splenic arteriography in splenic trauma. Am J Surg 127:310-313, Mar 1974

Kai Haber, M.D. Department of Radiology University of Arizona Medical Center Tucson, Ariz. 85724

Echographic evaluation of splenic injury after blunt trauma.

In a significant number of patients with blunt abdominal trauma, the diagnosis of ruptured spleen is not readily apparent. Is is in these cases that e...
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